Why do my legs feel so stiff?

By Dr. Aaron Case BSc, DC (April 2009)
micro tears

When you exercise, especially if you have gone farther or faster than you normally do, you might feel a bit stiff after your run. For the most part, it is because exercise causes micro tears in your muscles (see image to the right).

Micro tears sound worse than they are – they are actually a good thing because they create an opportunity for the muscles and tendons to rebuild stronger. This improved durability better prepares you for the next run. Basically,micro tears are part of how your body repairs itself and learns from experience.

Micro tears heal after exercise when the edges of the micro tears heal and unite again. This process is like when you cut your skin and get stitches or put on a butterfly band aid to hold the torn edges together. If you pulled or stretched apart the cut you would delay healing, so why would you stretch your legmuscles after an especially long or hard run?  Research does not support that stretching after a run improves recovery or makes you less sore; some people may even delay recovery or be more sore.

   Another analogy would be whiplash, which is more serious tissue damage/micro tearing in your neck. If you have even had the unfortunate circumstance to experience whiplash, you probably found that you had a very stiff neck for the next few days. It may have even hurt to stretch your neck. Depending on the severity of the whiplash, you also may have noticed that each day as healing took place that your range of motion returned without having to stretch (although gentle range of motion exercises may have helped to improve circulation and prevent adhesions/scar tissue from forming).

What should I do?

Often, when our bodies feel stiff, we do static stretches. However, static stretching may cause us to pull our micro tears further apart and hinder the repair process. So given the above information, you may want to consider adjusting your post-stiff-run routine.

plyometricsSometimes after long or hard runs, my legs feel stiff. In these cases, I refrain from static stretching that day and just let the healing begin. An ice bath or compression socks/pants may help recovery, but proper rest and nutrition are most important/effective. Depending on how much damage I cause to my legs (based on the newness of the distance, route and/or speed), I may start to feel my legs start to loosen up a day or two later. Prior to my next run a day or two later, I may do a few active stretchessuch as leg swings, lunges or heel drops to activate my muscles and to return to my previous range of motion.

That being said, static stretching after a long hard run does help some runners. For people who are very consistent with static stretching post runs, their bodies are likely able to tolerate the extra stretching and perhaps additional micro tears that the stretching itself may be causing. If stretching is working for you, please don’t stop, especially if you have a regular routine. After all, research indicates that inconsistent static stretchers get injured more than people who don’t stretch at all or for those who stretch consistently.

I encourage you to think about your post-stiff run routine and adjust it as you see fit or simply leave it be because, if it works for you, that is the best research because you know your body best.